How do I create a C# app that decides itself whether to show as a console or windowed app?

Question

Is there a way to launch a C# application with the following features?

1. It determines by command-line parameters whether it is a windowed or console app

Answer 1

The important thing to remember to do after AttachConsole() or AllocConsole() calls to get it to work in all cases is:

if (AttachConsole(ATTACH_PARENT_PROCESS))
  {
    System.IO.StreamWriter sw =
      new System.IO.StreamWriter(System.Console.OpenStandardOutput());
    sw.AutoFlush = true;
    System.Console.SetOut(sw);
    System.Console.SetError(sw);
  }

I have found that works with or without VS hosting process. With output being sent with System.Console.WriteLine or System.Console.out.WriteLine before call To AttachConsole or AllocConsole. I have included my method below:

public static bool DoConsoleSetep(bool ClearLineIfParentConsole)
{
  if (GetConsoleWindow() != System.IntPtr.Zero)
  {
    return true;
  }
  if (AttachConsole(ATTACH_PARENT_PROCESS))
  {
    System.IO.StreamWriter sw = new System.IO.StreamWriter(System.Console.OpenStandardOutput());
    sw.AutoFlush = true;
    System.Console.SetOut(sw);
    System.Console.SetError(sw);
    ConsoleSetupWasParentConsole = true;
    if (ClearLineIfParentConsole)
    {
      // Clear command prompt since windows thinks we are a windowing app
      System.Console.CursorLeft = 0;
      char[] bl = System.Linq.Enumerable.ToArray(System.Linq.Enumerable.Repeat(' ', System.Console.WindowWidth - 1));
      System.Console.Write(bl);
      System.Console.CursorLeft = 0;
    }
    return true;
  }
  int Error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
  if (Error == ERROR_ACCESS_DENIED)
  {
    if (log.IsDebugEnabled) log.Debug("AttachConsole(ATTACH_PARENT_PROCESS) returned ERROR_ACCESS_DENIED");
    return true;
  }
  if (Error == ERROR_INVALID_HANDLE)
  {
    if (AllocConsole())
    {
      System.IO.StreamWriter sw = new System.IO.StreamWriter(System.Console.OpenStandardOutput());
      sw.AutoFlush = true;
      System.Console.SetOut(sw);
      System.Console.SetError(sw);
      return true;
    }
  }
  return false;
}

I also called this when I was done in case I needed command prompt to redisplay when I was done doing output.

public static void SendConsoleInputCR(bool UseConsoleSetupWasParentConsole)
{
  if (UseConsoleSetupWasParentConsole && !ConsoleSetupWasParentConsole)
  {
    return;
  }
  long LongNegOne = -1;
  System.IntPtr NegOne = new System.IntPtr(LongNegOne);
  System.IntPtr StdIn = GetStdHandle(STD_INPUT_HANDLE);
  if (StdIn == NegOne)
  {
    return;
  }
  INPUT_RECORD[] ira = new INPUT_RECORD[2];
  ira[0].EventType = KEY_EVENT;
  ira[0].KeyEvent.bKeyDown = true;
  ira[0].KeyEvent.wRepeatCount = 1;
  ira[0].KeyEvent.wVirtualKeyCode = 0;
  ira[0].KeyEvent.wVirtualScanCode = 0;
  ira[0].KeyEvent.UnicodeChar = '\r';
  ira[0].KeyEvent.dwControlKeyState = 0;
  ira[1].EventType = KEY_EVENT;
  ira[1].KeyEvent.bKeyDown = false;
  ira[1].KeyEvent.wRepeatCount = 1;
  ira[1].KeyEvent.wVirtualKeyCode = 0;
  ira[1].KeyEvent.wVirtualScanCode = 0;
  ira[1].KeyEvent.UnicodeChar = '\r';
  ira[1].KeyEvent.dwControlKeyState = 0;
  uint recs = 2;
  uint zero = 0;
  WriteConsoleInput(StdIn, ira, recs, out zero);
}

Hope this helps...